The present invention relates to electric discharge lamps and other similar electrical discharge devices.
Electric discharge lamps are known per se. For example, U.S. Pat. No. 6,400,089 and U.S. Pat. No. 7,199,374, the disclosures of which are hereby incorporated herein by reference, disclose corona discharge lamps. In such devices, a negatively charged electrode is spaced apart from a grounded counter electrode in a chamber containing an excimer-forming gas. The negatively charged electrode is typically highly curved (e.g., forming a sharp point or a wire with a small radius), while the grounded electrode typically has low curvature (e.g., in the shape of a flat plate). Applying a high negative voltage to the highly curved negative electrode creates a high intensity electric field around the negative electrode, which provides emission of free electrons. Near the negative electrode, the high field accelerates free electrons to an energy level sufficient to cause excimer formation. An excimer is a short-lived molecule which typically consists of two atoms in an excited or high-energy state, and may include atoms which will not normally bond with one another in the unexcited or ground state. Remote from the negative electrode, the field is lower, and is below the level required to substantially ionize the gas. By configuring the electric field to accelerate electrons to at least the energy required to form excimers in one portion of the field, while keeping the field strength in at least one region of the field below that required to substantially ionize the gas, an arc will not form between the negative electrode and the counter electrode. Such a non-arcing discharge is referred to as a corona discharge. In one application, the excimers emit electromagnetic radiation such as light upon decay of the excimers. For example, certain noble gas containing excimers will emit ultraviolet light upon decay. If the wall of the chamber is transparent or translucent to the light generated by the decay of the excimers, the light can pass out of the chamber.
Further improvement in the construction of such discharge devices would be desirable.